Answer:
If you mean limitations with the argument that religion is the source of morality, then you should read The God Delusion. There is a section about this topic. In it, there is a study involving people being asked questions with a morally right answer, such as "Five people are dying from five different organ failures. Should you take these organs from a healthy man sitting in the lobby of the hospital?" The "right" answer is "no." These questions become more complex and there are many. Anyways, the results showed that people who are not religious did not do any differently than people who are. One might say that an atheist got his morality from religions of the past, which were then considered to be truth. This is refuted by that study, because they did the same thing with a tribe that had absolutely no exposure to any religion (of course with questions involving situations that they would understand) and the results were the same. Therefore, it is simply human nature to be moral.
If you meant what are the limitations of basing your morality on religion, then there aren't really any. What most religions teach about what is right and wrong is good. I just don't believe that religion is what created morality. I believe people have always had a sense of morality and that it was then incorporated into religion. But if someone bases their morals off of religion, they'll probably be a good person.